Heat-resistant Steel Precision Castings of Production Process
Heat-resistant steel is generally smelted in an electric arc furnace or induction furnace. High quality requirements often use vacuum refining and out-of-furnace refining processes.
Some high-alloy heat-resistant steels are difficult to process and deform. The production of castings is not only more cost-effective than rolled products, but also castings have higher endurance strength. Therefore, heat-resistant cast steel occupies a considerable proportion of heat-resistant steel.
Heat-treated pearlitic heat-strength steel is usually used after normalizing or quenching and tempering.
Martensitic heat-resistant steel is quenched and tempered to stabilize the structure and obtain good comprehensive mechanical properties and high-temperature strength.
Ferritic steel cannot be strengthened by heat treatment.
In order to eliminate the internal stress caused by cold plastic deformation processing and welding, annealing treatment can be carried out at 650～830℃, and rapid cooling after annealing, so as to quickly pass through the brittle temperature range of 475℃.
Most of the austenitic anti-oxidation steel adopts high temperature solution heat treatment to obtain good cold deformation. Austenitic hot-strength steel is first treated with high-temperature solution treatment, and then aging treatment is performed at 60-100℃ higher than the use temperature to stabilize the structure.
Heat-resistant cast steel is mostly used in the as-cast state, and some heat treatments are used according to the type of heat-resistant steel.
Production process of heat-resistant steel precision castings
1. Determine the production process and check the mold according to the drawings provided by the user. If it is a new product, prepare it, determine the molding process, and send it to the mold maker to make a wooden mold.
2. According to the finished mold, determine the manufacturing process and operation method, the specific steps are as follows:
- Put the resin sand into the sand mixer according to the old and new ratio and mix it evenly.
- According to the quality of sand, in principle, add acid and resin according to the mass ratio to produce sand and fill the mold.
- After the surface is hardened, the mold will be awakened and demolded, then the mold will be repaired, and the mud core will be dropped. After the virtual sand has been blown out, it will be dried by itself after being ignited.
- Prepare the finished cavity according to the bottom cover box, seal the box and place the gate and riser for pouring.
3. Foundry smelting mainly involves the following preparations and operations:
- First, perform chemical analysis on the raw materials.
- Put a large piece of bottom material on the bottom of the furnace for pre-melting, and then gradually add small materials and scraps. When adding materials, be careful not to splash out the molten steel to avoid burns.
- Wait for the molten steel to melt into the furnace cavity.
- In the molten steel smelting process, in order to purify the molten steel, oxidation smelting is carried out, and the slag covering the surface is stripped off at the same time, and the steel is tapped immediately.
- The molten steel poured from the furnace cavity into the steel drum is secondarily oxidized. At this time, the aluminum row must be inserted for the second deoxidation. Care must be taken during the operation to avoid burns.
- When pouring, you must master the time, and wear protective clothing and safety helmets during the operation to be busy and not chaotic.
4. The product can be sanded at least four hours after pouring, and the finished product can be machined.
5. The quality inspection department inspects the manufactured products, including the secondary repair of geometric dimensions, surface shapes and defects. After each product is qualified, it will be solid-solution treated and marked with the word “inspection”, then packaged, dispatched, and dispatched. List and product warranty.
Heat-resistant steel precision castings of what are the factors that affect the production process
- Design process of iron castings. When designing, in addition to determining the geometry and size of the casting according to the working conditions and the material properties of the metal, the rationality of the design should also be considered according to the process characteristics of the casting and the casting alloy to avoid deformation, cracking and composition of the casting. Defects such as segregation.
- The casting process should be reasonable, that is, the appropriate modeling and core making method should be selected according to the structure, size and weight of the cast iron. In addition, the chilled iron, riser and gating system must be set reasonably to ensure the quality of cast iron parts.
- Whether the quality of raw materials for casting is excellent or not. If the quality of materials such as metal charge, solvent, modifier or paint does not meet the standard, it will cause defects such as porosity, slag inclusion, and sand sticking in the iron castings, which will affect the internal and appearance quality of the iron castings.
- The process operation procedures should be reasonable. When making castings, it is necessary to continuously improve the technical level of the workers, and at the same time, formulate reasonable process operating procedures to make the production process correct and reasonable.
Eternal Bliss Alloy Casting & Forging Co, Ltd.
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